U.S. Pat. No. 5,011,996 discloses Raney catalysts containing nickel and/or cobalt used in the presence of organic sulfur compounds to catalyze hydrogenation of reaction products of oxo compounds with amines or ammonia to the respective amines.
U.S. Pat. Nos. 4,826,799 and 4,895,994 are directed to catalysts made by the Raney process and pelletized in a matrix of polymer and plasticizer. Each makes a broad disclosure of Raney process alloys consisting of 45-75 weight % Al and 25-55% of a conventional Raney process metal, e.g., Ni, Co, Cu, or Fe, or mixture of these. Promoters may also be present such as Cr, Mo, Pt, Rh, Ru, Os, and Pd, typically at about 2 weight % of total metal.
U.S. Pat. No. 2,257,814 describes hydrogenation of dinitriles in the presence of mild-acting catalysts prepared by leaching an alloy of aluminum, iron and cobalt with an aqueous alkaline solution to provide the catalyst which contains 5% to 10% by weight of cobalt and 95% to 90% by weight of iron. The rate of hydrogenation of adiponitrile using this catalyst (as shown in Example 3B, below) is much too slow to provide a viable commercial process.
U.S. Pat. No. 5,151,543 reports a process for selective hydrogenation of aliphatic dinitriles to aminonitriles under low pressure with high yield using a Raney-type catalyst selected from the group consisting of Raney nickel, Raney cobalt, and Raney nickel promoted with metals or metal oxides selected from Group VIB or promoted with ferrous metals of Group VIII of the Periodic Table. Thus, in this catalyst, iron, if used at all, would be present in only low concentrations.
Sokol'skii, D. V., T. Kh. Avetisyan and A. S. Khlystov, Zh. Prikl. Khim. (Leningrad), 56 No. 1, pp 23-26 (1983). Raney-type cobalt-iron catalysts were prepared from alloys of the following compositions: 75Al--5Co--20Fe, 75Al--10Co--15Fe, 75Al--15Co--10Fe, and 75Al--20Co--5Fe. Variation of the phase composition and properties of these cobalt-iron catalysts were studied by Mossbauer spectroscopy during the hydrogenation of ethynyldimethylcarbinol. This publication did not disclose a combination of three metals used with aluminum to prepare Raney-type catalysts.
PCT/Fr95/01643 claims a process for the hemi-hydrogenation of aliphatic dinitriles using hydrogen in and a Raney nickel or; Raney cobalt catalyst, where the Raney nickel catalyst also contains a dopant chosen zinc and the elements of Groups IVb, Vb, VIb, VIIb and VIII of the Periodic Table, and where the Raney cobalt catalyst also contains a strong inorganic base and a dopant chosen zinc and the elements of Groups IVb, Vb, VIb, VIIb and VIII of the Periodic Table. It is also disclosed that the dopants usually represent from 0% to 15% and preferably from 0% to 10% of the weight of nickel or cobalt.
WO97/37963 discloses Raney catalysts for hydrogenation of compounds containing at least one unsaturated carbon-nitrogen bond. The catalysts contain cobalt and/or iron and can be modified with metals of Groups VIb (Cr, Mo, W) and VIII (Ru, Os, Rh, Ir, Pd, Pt) of the Periodic Table as well as Cu, Mn, and Re. The content of cobalt or iron in the catalyst is generally in the range of 50-99.9% by weight, preferably 80-99% by weight relative to the active components (cobalt and/or iron+modifying agent).
An object of the present invention is to provide a Raney catalyst having high selectivity, high reaction rates and long service lives. The presence of the small quantity of the third Group VIII metal in the Raney catalyst composition provides faster rates of hydrogenation than do catalysts consisting only of cobalt and iron. The ratio of iron to cobalt in these catalysts assures long reaction life.
A more specific object of this invention is to provide a Raney metal catalyst which has a low ingredient cost and is suitable for use in continuous operation to give a stable reaction rate and product selectivity in low temperature, low pressure hydrogenation of adiponitrile (ADN) to 6-aminocapronitrile (ACN) and/or hexamethylenediamine (HMD).